Process for manufacturing benzol and valuable by-products from butane, propane, or ethane, or mixtures thereof



Oct. 7, I930. PORTER 1,777,894

PROCESS FOR MANUFACTURING BENZQL AND VALUABLE BY-PRODUCTS FROM BUTANE,PROPANE, OR ETHANE, OR MIXTURES THEREOF Filed April 2'7, 1927 3Sheets-Sheet 1 INVENTOR ffPa/wf/P BY v 7% ATTORNEY Oct. 7, 1930. PORTER1,777,894

PROCESS FOR MANUFACTURING BENZOLAND VALUABLE [BY-PRODUCTS 7 FROM BUTANE,PROPANE, OR ETHANE, OR MIXTURES THEREOF Filed April 27, 1927 3Sheets-Sheet 2 Oct. 7, 1930. I PORTER 1,777,894

, PROCESS FOR MANUFACTURING BENZOL AND VALUABLE BY-PRODUCTS FROMBUTANEpPROPANE, OR ETHANE, OR MIXTURES THEREOF Filed April 27. 1927 V I5Shee'ts-Sheet 3 said process maybe e Patented Oct. 7, 1930 UNITED STATESPATENT OFFICE ram ron'rnmor some error,

OKLAHOMA, ASSIGNOB, BY HESNE ASSIGNMENTS,

'I'O CONTINENTAL OIL fOl' PONCA. CITYrDKlJAEOML, A CORPORATION 01 nrmawm:enocnss FOB mnracrnnmg mnrzor. nm'vamiannn nY-raonuc'rs mom Burma,

rnorsna on. manna, on mxrvnns, rnaasor a lic tion filed April :7, 1927.Serial m. 188,851.

by valuable by-products a number of compoundswhich are produced alongwith ben- 1 zol by my process, and of which'the followin is a partiallycomplete list and may be tafien as examples of others of, similarcomposition and having similar properties. The term may be understood toinclude either the separate purified or partially purified compounds ormixtures of a number of the said compounds in varying proportions, ofwhich the following are examples: toluene, xylenes, naphthalene,phenanthrene, .ethylbenzene, 'propylbenzene, cumene, pseudo-cumene,cymene, mesitylene, methyl naphthalene, ethyl 26 naphthalene, acetylene,ethylene, propylene andhydrogen. The operation upon the hydrocarbon gasto produce the benzol and valuable by-products' will be designated ascracking?.

It is a well known fact that small amounts of aromatic hydrocarbons maybe made by heating hydrocarbon gases to a high temperature. Previously,however, the exact conditions have notbeen specified such as to' makethe yield sufliciently large, nor has an a paratus of such anarrangement been designed orconstructed as to make the manufacture ofbenzol from such gases a venture of any considerable commerclalimportance. The primary object of this invention is to provide a processin which the hydrocarbon gases are treated at the proper tem eraturesand for the proper .time, and un er other conditions hereinafterspecified, so as to give ields of benzol and valuable by-products argerthan heretofore obtained.

Another object of the present invention V is to r'ovide a process forthe extraction and puri cation of said benzol and valuable byproducts.

of the mixture so obtained and the ex- 1 shall designate referencecharacters 1 and 2 in' Fig. I one of which is shown more fully in Fig.II

A furtherobject of the invention-isto provide apparatus suitable tocarry out the above-mentioned processes.

In the accompanying drawings are shown examples-of my apparatus indiagrammatic form 1n which the process herein specified may be carriedout.

Fig. I shows one form of apparatus which I shall designate as theintermittent form.

'Fig. II illustrates one of my furnaces, partially in elevation andpartly in vertical sect on.

Fig. III illustrates an optional form of apparatus which I may employand which I shall designate as the continuous form of apparatus forcarrying out the process.

The furnaces which are designated by the and contain each a large amountof surface such as obtained by the use of a checker of brick A of somerefractory material, such as fore clay or silica, and are providedeachwith a gas inlet Band a gas outlet C. The fur naces 1 and 2 areinternally heated by a burner from which the 'flame and hot gas come indirect contact with the checker brick, said heating taking place beforethe gas to be cracked is passed through the furnace. When the furnacehas been heated sufficiently the burner is closed off, the port at whichthe flame entered is closed, and the gas to be cracked is passeddownward through the furnace tortuously, where, under the influence ofthehigh temperature within the fur nace, the benzol and valuableicy-products are formed. For smoothness of operation the furnaces areused alternately so that one is being'heated While the other is used forcracking. From the bottom of the furnace in which a cracking operationhas taken place the products pass out and are cooled in a heatexchanger- 24 by the cool air being supplied to the other furnace duringthe heating thereof,andthe liquid or material carried in suspension,designated as tar, is separated in the tar extractor 3 by settling,washing, centrifuging, electrical precipitation, or other means, or anycombination of these means of separation. The benzol is then separatedfrom the residual as by compression, oil absorption, or solid asorbents. In the drawing the compression methodis shown merely by way ofillustration. The compressor 4 compresses the gas after it has beenpassed through the furnace, after which the cooler 5 cools the gas andthe'li uid condensate ac.-

cumulates and is separate from the residual 'gas in the accumulator ortrap 6 (Fig. II).

In the intermittent form of apparatus just described, because the flameis withdrawn the temperature of the heating surface does not stayconstant, but decreasescontinuously as 'the furnace through the cell ofa katharometer or thermal conductivityunit 7. When the thermalconductivity unit 7 is properly adjusted so that gas cracked togive thebest yield caused the resistance bridge 8 to be in balance, I have foundthat slight variations from the proper flow cause the bridge to beunbalanced and that the deflection of the galvanometer 9 placed acrossthe bridge may be amplified by-means ofany one of a number of devicesknown to those skilled in the art to obtainan impulse sufficient toadjust a throttle valve 11 on the direct line supplying the gas to'thefurnace. The arrangement is such that the throttle valve is adjusted inthe direction to give the preiper flow through the.

furnace for the best yiel This in turn tends to bring the bridge intobalance.

I am aware that other physical properties of the cracked gas, such asspecific gravity,

7 might be arranged byone skilled in the art to operate the 'inletvalvein much the same manner.

The ports as valves 14,15, 16, 17, 18, 19,-

20, 21, 22 and 23,, with the exception of the throttle valve describedabove are operated I I by a cam which is operated by a clockwork and isadjusted to bring about the proper cycle of heating and cracking, butfor s1m-. plicity I have not shown the cam or clockwork in the drawing.

In Fig. I, I have shown, for simplicity, only two furnaces, but it isobvious that more than two may-be used, or that other parts may beconstructed in multiple without alteringthe character of the invention,V

In Fig. III there is shown an' o 'tional apparatus which-I have desi'gna.as a continuous form. The gas isp'assedthrough a heat exchanger 25,where heat is transferred toit from the hot cracked gas. The gas is thenpassed through a series of pipes 26 enclosed in a furnace 27. ..Thetemperature of t-he'furnace' andthe flow of the gas is adjusted so thatthe gas is properly cracked.

It is important to construct the tubes in which the gas is heated in thefurnace of a material that does not exert a harmful catalytic efi'ect onthe yield of benzol. I have'found thatiron and nickel and similar metalshave a not suitable as a material from which to construct the heatingsurface. They may be used only when coated witha material which pro.-tects the surface'from coming in contact with harmful catalyticinfluence and are therefore the gas. Forexample, 'I have found that aniron tube coated with chromium or tin is suitable for use as a heatingsurface inside the furnace. The procedure for the extraction of tar andthe recovery .of the benzol is the same in the continuous as in theintermittent form of the apparatus, and is therefore not shown in Fig.III.

The separation and purification of the benzol andvaluable liquid orsolid by-products may be accomplished b any of the methods now known tothe art 0 manufacture of such products fromcoal gas.

The separation ofacetylene from the cracked gas may be accomplished bythe use of an organic solvent, such as acetone, which is circulated inan absorber continuously,

countercurrent to and in direct contact with the stream of. gas, andthence-to 'a still where the acetylene-is separated by heat or reducedpressure, or both. An optional method is the use of an aqueous solutionof a metallic salt, such as ammoniacal cuprous chloride, with which theacetylene reacts to form a metallic acetylide. The solution is thenregenerated by heatin or by the addition ofv acids, until the acetyeneis' removed, and then bringing it back to its'original alkalinity forrecirculating.

The acetylene may by an optional process be separated by absorption inactivated charcoal. After the charcoal is'saturated with "acetylene, theacetylene is distilled from the tional' acetylene extraction processesdescribed above.

The acetylene and benzol may, by an optional process, be extracted atthe same time by means of activated charcoal.

It has been found that the greater the proportions of butane, propane orethane taken in order in the gas, the greater the yield of benzol willbe, and for this reason it is high- 1y desirable to use the gas fromrectifiers, stabilizers, or recoinpressors in use in the naturalgasoline industry. p

The temperature to which the gas must be heated depends, as previouslyindicated, on the time to which it is subjected to the temperature. Ineneral, it may be stated that the proper crac ing tem erature to whichthe gas must reach'ranges romaround 825 C. to 950 C.

The tar produced contains very little, less than 1 percent, of phenoland cresols or aromatic compounds containing oxygen, ni-- trogen, orsulfur and should have uses where the presence of these bodies areobjectionable and where, therefore, the use of tar produced from :thedestructive distillation of coal is not feasible.

The gas producedis almost free from sulfur compounds, containing lessthan 1 'percent thereof, and should serve as a valuable raw material forthe manufacture of products where contamination with sulfur compoundsare undesirable. I have found that the gas may contain around 1 percentto 2 percent acetylene, around 7 percent unsaturated h drocarbons of theethylene group, and t at it may contain as much as material containinilying between met ane andpentane in the homolo ous series by materiaover bricks o fire-resisting ,qualities, and separating the benzoland'valuable by-products thus 0 rmed from the residual sists in heating to atemperature between 800 C. and 950 C. a gaseous hydrocarbon materialcontaining saturated-hydrocarbons lylng between methane and pentane inthe homolo one series by passing said gaseous materia over a' heatednon-ferrous surface,

and separating-the benzol and valuable byproducts thus formed from theresidual gas: In testimony that I claim the foregoing I hereunto afiixmy signature.

- FRANK PORTER.

50 percent hydrogen. All these constituents- I have added sulfur.

Provided value,.due to the low percent of tubes or material other thaniron, nickel, or similar metals are used, only a small percentage of thegas entering the tubes in the continuous process is decomposed accordingto a side reaction with the deposition of carbon black. However, the

residual gas.

small amount that does ccur maybe removed periodically by' interruptingthe flow of gas to be cracked and passing instead'air,

steam, or carbon dioxide or sesgcontainin a considerable proportion 0these throng the tubes while they are at a high enough temperature forthe carbon to react with said gases and be removed as carbon monoxide.

Various changes in the specific process herein described and in thespecific apparatus as shown and described ma be made within the scope ofthe claims without materially departing from the spirit of my inmanufacture of assing said gaseous saturated hydrocarbons "gas. 1

3. The (process for the manufacture of benzol an valuable by-pro'duets,which con- Ill between met ane and pentane in the ho'molo- I gousseries, and separating the benzol and valuable by-products thus formedfrom the 2. The process for the manufacture of i benzol and valuableby-produets, which consists in heating to a temperature between 800 C.and 950 C. a gaseous hydrocarbon

